Cross lapping apparatus and process



Dec. 29, 1970 D. w. TROTT 3550,35

CROSS LAPPING APPARATUS AND PROCESS Filed Jan. 18, 1968 INVENTOR fifiavid W. Twit ATTORNEY United States Patent Office 3,550,215 Patented Dec. 29, 1970 3 550 215 CROSS LAPPING AEPAEATUS AND PROCESS David W. Trott, Charlottesville, Va., assignor to Celanese Corporation, New York, N.Y., a corporation of Delaware Filed Jan. 18, 1968, Ser. No. 698,842 Int. Cl. D04h 11/04 U.S. Cl. 19-163 3 Claims ABSTRACT OF THE DISCLOSURE A method of producing a nonwoven batting from a lightweight web of continuous filaments by cross lapping the lightweight web and an apparatus for cross lapping such lightweight webs at increased speeds, efiiciencies and uniformity.

BACKGROUND OF THE INVENTION This invention relates to the production of batting materials and an apparatus therefor.

Cross lapped battings have been previously known and prepared by various methods. More recently, methods have been developed for producing lightweight webs of continuous filaments whereby the lightweight webs can be cross lapped into heavier weight battings of high bulk. Such battings are particularly useful for the production of cushioning materials such as pillows, mattresses, furniture cushioning and the like. The fibrous web produced is normally of a lightweight construction such as less than about 1 pound per square yard and more preferably less than /2 a pound per square yard. Many of these Webs have a weight measured in a few ounces or fractions of an ounce per square yard.

An apparatus and process for producing batting materials from continuous filament tows is described in United States patent application Ser. No. 568,877, filed July 29, 1966 in the name of George A. Watson, assigned to the same assignee as the present application. The present application describes an improvement in the process and apparatus described by Watson and therefore, the disclosure of Watson is hereby incorporated into the present specification.

While the apparatus described by Watson produced excellent battings from lightweight webs it was found that the nature of the lightweight web tended to limit the speed of operation of the apparatus due to the delay caused by the falling of the web onto the collection means The extremely lightweight web tended to parachute slowly onto the collection means due to its buoyancy in air. r

One object of the present invention is. to provide a novel, economical and highly efficient method for cross lapping light-weight webs of substantially parallel continuous filaments at increased speeds and etficiencies. An-

other object of the present invention is to provide a method and apparatus for improving the uniformity of cross lapped products. Other objects of this invention will become apparent to those skilled in the art from the description which follows.

DESCRIPTION OF THE INVENTION In accordance with the invention, an apparatus is provided for cross-lapping lightweight webs by means of a traversing structure which supplies a longitudinally moving lightweight web of continuous filaments onto a moving collection means by alternately moving the web in opposite directions across said collection means while depositing the web in a folded condition onto said collection means, the improvement comprising gas jet means positioned above said collection means and said web, said jets being positioned across the width of said web and being directed downwardly onto said web at an acute angle to the traversing means. In addition, the present invention is directed to the process of operating said cross lapper wherein a high-volume air source of relatively low pressure is directed onto the falling web thereby substantially overcoming the air buoyancy of the web.

The present invention finds its greatest utility in the handling of fine, lightweight, diaphanous, flexible, cohesive, spread webs of substantially parallel, crimped continuous filaments as described for example in Belgian patent 656,031 and the corresponding South African patent application 64/5387. The present process and apparatus substantially overcome the problem caused by the buoyancy in air and the air turbulence created by the rapid passage of the cross lapper over the collection means. By the present method and apparatus, the lag time required for the freely falling web to reach the collection point is significantly reduced. Thus, the speed of operation can be increased while at the same time, improving the uniformity of the cross-lapped batting produced.

DETAILS OF THE INVENTION The invention will be more fully described by reference to the drawings in which;

FIG. 1 is a perspective view of one type of cross lapping apparatus particularly useful with the present invention showing one means for positioning the gaseous jet means; and

FIG. 2 is a sectional schematic showing the path of the web in relationship to the position of the gas jets during the traverse movement of the cross-lapping apparatus.

Referring to FIG. 1, which illustrates a preferred type of cross lapper, a wide, spread web 9 of deregistered, crimped, substantially parallel, continuous filaments is supplied continuously to a pair of feed rolls 11 and 12. The web drops down from the feed rolls into a wide pivoted chute 13 made up of a pair of relatively closely spaced rigid panels or doors 14 and 16 which are mounted for oscillating or swinging movement together about pivotal axis 17. The web passes downward between the doors 14 and 16 and is distributed, by their oscillating action, back and forth across a continuously moving apron 18 (which is preferably a moving endless belt) to form cross-lapped batting 19.

Web 9, which may be 20 to inches or more wide for example, may be produced from a crimped tow of a great many continuous filaments such as 30,000 or more or less, by passing the tow through a banding device to straighten the tow, a threaded roll device to deregister the crimps of adjacent filaments and a series of air spreaders which subsequently spread the tow to a lightweight web. This web 9 is fed to a cross lapper as illustrated in FIG. 1. The foregoing procedure is described in detail in the previously mentioned Belgian patent.

The unitary oscillating movement of the two doors 14 and 16 may be effected in any suitable manner, as by mechanical means pneumatic or hydraulic cylinder 33, wherein the flow of fluid to the cylinder is regularly reversed by a suitable valve 34 controlled in turn by adjustably mounted limit switches 36, 37 which are engaged by laterally extending projections on the doors. Thus, when the doors reach the predetermined limit of their swing in either direction a limit switch 36 or 37 is tripped by one of these projections, causing the piston of the cylinder 33 to reverse its direction of movement.

While various types of traversing means can be used, the use of a chute 13 makes it possible to produce battings whose width is considerably greater than the traverse distance of the lower end of the chute. For example, battings of about 84 inches wide have been produced with a traverse distance of only about 48 inches. This effect is particularly noticeable when the web is fed at a high speed. While not wishing to be bound by any particular explanation, it is believed that this effect is attributable to the air currents and dynamics generated in the operation of the device. However, this generated air current which is particularly useful for extending the width of the cross lapped material is also the source of the limiting factor of cross lapping speeds.

The present invention involved the placement of gas jet means 30 which are capable of issuing a large volume of relatively low pressure air or other gaseous medium such as steam, onto the top of the falling web being cross lapped. Preferably, the gaseous jets need only be operated during the back stroke of the cross lapper such that gas issues alternately from both sides of the cross lapper during the back stroke thereof. However, it is readily recognized that under certain operating conditions it may be desirable to operate the apparatus wherein gas continuously is exhausted from the jets during both the forward and backward movement of the cross lapper.

The gas jet supply apparatus 28 and 29 is conveniently operated under a surge tank effect wherein a plurality of gas jet outlets 30 are positioned along the lower side of tanks 28 and 29. While a plurality of jet openings have been found to be particularly suitable, a narrow slit spanning the length of the tank can also be used.

The tanks 28 and 29 are of sufficient size to supply the desired amount of gas to jets 30 in the desired manner wherein a high volume of gas at relatively low pressure contacts the fibrous web. Conveniently, gaseous supply means from compressed air, nitrogen, steam and the like are connected to tanks 28 and 29. Surge tanks 28 and 29 are supplied with shut off valves which are actuated in accordance with the swing of the cross lapper such as being actuated by limit switches 36 and 37 or in the like manner desired for the particular cross lapping operation.

While the gaseous jet supply need not be attached directly to the cross lapping apparatus, it has been found to be most desirable as such attachment readily provides the air flow in the desired direction. It is particularly desirable to position the gas jets so as to direct the flow of air at an acute angle away from the side Wall of the cross lapping apparatus and the path of the web falling through such apparatus. In particular, when measured as noted in FIG. 2, the angle of jet direction formed with the plane of web 9 falling through chute 13 and passing through the jet openings 30 is an acute angle alpha (a) of about to 70 degrees and more preferably about to 60 degrees. Angle alpha is varied, depending on the height of the jets above the outlet of chute 13, the angle of the cross lapping swing the width of cross lapping and the like. It has been found that by adjusting the jet angle so that gas fiow from the jets impinges initially upon the outer fold 32 of the falling web and then sweeps forward toward the center of the web with the movement of the swinging cross lapper, the most efficient lay down of web is achieved.

Gas jet means 28 and 29 are preferably positioned on the lower ends of doors 14 and 16. The jets 30, as noted above, preferably exhaust a relatively high volume of gas such as air from the gas chamber which is maintained at a relatively low pressure of about 0.05 to 15 pounds per square inch gauge pressure. The a tual v 1- ume of air exhausted can be varied widely, depending on the various factors such as the speed of operation, the weight of the web being cross lapped, the width of the cross lapped batting and the like. The most preferred gas pressure and volume of exhaust gas is readily determined empirically for the particular web depending on the weight of the fabric, the strength thereof, the air permeability thereof and the like. The jets, of course, are regulated so that the velocity does not pierce, deform or tear the web being laid down. Normally, the series of jets will exhaust about 0.5 to 10 cubic feet of gas per minute in a conventional operation wherein a web of about 50 inches in width is being cross lapped. In a typical embodiment, jets of about Ms inch diameter openings, spaced about 2 inches apart and operated at a gas chamber pressure of about 0.1 to 1 pounds per square inch gauge have been found to provide the desired volume and pressure for webs of less than about /2 ounce per square yard.

As noted above, in place of individual gas jets, a slit jet can be used to thereby exhaust a band-like gas stream across the length of the web being laid down. In such an embodiment, similar gas volumes and pressures are used.

While the invention has been described more particularly with respect to lightweight webs of substantially continuous parallel crimped filaments, it will be readily recognized that the present apparatus and method can also be used with other types of webs such as staple fiber battings, cheesecloth, high yield tricot and the like, particularly lightweight materials below about 1 ounce per square yard. Heavier webs can also be utilized in the present invention to thereby obtain correspondingly good results.

When the present process is utilized in connection with a plenum chamber for blowing the falling web outwardly away from the lower opening of the cross lapper, thus increasing the width to which the cross lapper can lay the web as described in the aforementioned Watson application, the presently described air jets are preferably synchronized so as not to conflict with the initial billowing of the web.

It will also be recognized that the present process and apparatus can be facilitated by the use of a porous or foramorous collection means to permit a more rapid route of escape for gases held under the falling web. Additionally or alternatively, slightly reduced pressure or exhaust systems can be used in conjunction with the collection means to assist in the increased speed of web lay-down.

The described jets of the present invention can also be utilized to serve a multi-function such as for applying a bonding agent, colorants, solids and the like as may be desired along with the blast of gas.

While there have been described various embodiments of the present invention, the methods and elements described herein are not intended to be understood as limiting the scope of the invention as it is realized that changes therein are possible. It is intended that each element recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner. It is intended to cover the invention broadly in whatever form its principles may be utilized being limited only by the appended claims.

I claim:

1. A process for the production of a cross laped structure comprising continuously guiding and traversing a free falling longitudinally moving web of filamentary material across a collection zone while feeding said web onto said zone to deposit said web in a folded condition onto said collection zone, said traversing operation comprising the step of continuously directing a stream of gas at a pressure of from about 0.05 0t 15 pounds per square inch gauge downwardly onto said web during its movement to said collection zone at an angle of from about 10 to 70' degrees from the downwardly feeding direction of said traversing web, said gas stream being directed alternately then sweeps forward toward the center of the web as onto the top side of the traversing falling web forcing the web is traversed across the collection zone. zairtl W31) dolvlvngardflynonto staid fcollelctiorg zone at a rate References Cited aser ant e ree a ingraeo sal we 2. The process of claim 1 wherein the gas stream is 5 UNITED STATES PATENTS directed downwardly onto said web at an angle of about 2,863,493 12/1953 SIIPW et 73 20 to 60 degrees from the downwardly feeding direction 2 fig' gg f ray 0 traversmg Web 3,192,572 7/1965 Gordon 19-161 3. The process of claim 1 wherein the gas stream impinges initially upon the outer fold of the falling web and 10 DORSEY NEWTON, Primary Examiner 

